Electrical apparatus.



K. C. RANDALL. ELECTRIGAL APPARATUS.

APPLICATION FILED JULY 28, 1909.

999,870. Patented Aug. 8,1911.

4 NVENTOR m1: 6 flwbw ATTORNEY UNITED STATES PATENT OFFICE.

KARL C. RANDALL, OF EDGEWOOD PARK, PENNSYLVANIA ASSIGNOR TO WESTING-HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYL-VANIA.

Appucationfiled July 28, 1308.

Specification of Letters Patent.

ELECTRICAL A PPARA'IUS.

Patented Aug. 8, 1911.-

Serial No. 509,984.

oi lldn'ewood Park. in the count of Alle- ,g'hen and State ofPennsylvania, have iiiveuted a new and useful Improvement 111 l.lectrical Apparatus, of which the following is a specification.

My invention relates to electrical apparatusyaml it has specialreference to t'ansformers and other devices which are provided with.inclosimgtanks or casings wholly or partially tilledwith air or otherfluids.

The object o't my invention is to provide means for preventing acondensation of u'loisture within the casings of devices of the classabove indicated that shall be Slll'lPlQ and lllOXPQllSlYQ inconstruction and etlicient in operation. I

\Vhcn transformers and other electrical devices are inclosed in tanksand are located in the open air, changes in the outside temperature,relative to the temperature within, will frequently cause a so calledbreathing action," which term is ordinarily applied to such a transferof air from outside to inside as causes a condensation of moisture onthe traniormcr coils and on the insideof the lven though the air whichis withcasing. in the transtormcr casing is ordinarily pert ectly dry,'the increase of temperature within causes air to be forced out ofthe casing and, as the transformer assun'ics alowcr temperature, outsideair chargedwith moisture will enter the 'asin As this process isrepeated, a material amount of moisture will accumulate and endanger theinsulation of the apparatus, particularly if it is used in highpotential service.

According to my present invention, I provide mcansjtor holding the-airwithin the transtorn'icr casing at a pressure which is slightly greaterthan that of the outside atmosphere in order that any flow of air may beoutward instead of inward. In order to compensate For any small leak inthe transformer casing, a constant supply of air is n'iaintained.

The single figure of the accompanying drawing is a diagrammatic planviewo'f a plurality of transformers, the tanks of which are connected tothe pressure-producing apparatus of my invention.

Referring to the drawings, transformers or other electrical apparatusare disposed within the casings 1, 2, and 3 which may be filled with airor partially filled with liquid insulation, a slight pressure beingmain-- taincd within the casing by means of a pump or blower i. Thispump produces a relatively high pressure within. a storage tank orreservoir 5 which is supplied from. the outside atmosphere through achambr'li containing hygroscopic material, the pressure being cut downby a reducing valve 7 'before it enters the transformer casings.

The storage reservoir maybe omitted but it will ordinarily befounddesirablc, in,

order to avoid the necessity of operating the pump continuously. Forexample, if the transformer tanks are practically free from leaks, anauxiliary reservoir may be filled with dry air, or some other suitablefluid, by operating a pump for a relatively short time, and several daysmay then elapse before it; is necessary to again operate the pump.

By maintaining a relatively low pressure in a large storage tank, thereducing valve may be omitted.

A relatively small pump will serve to sup-' ply the necc any pressure toa large number of transformershaving sealed tanks, since the pressure ofa few ounces will usually be found sutiicient to prevent the breathingaction.

I do not wish to be limited to the use-of dry air for preventingi'noisture from gathering on the transformer windings, since anysuitable insulating dchydrated fluid or combination of fluids may beemployed.

I. claim as my invention:

l. The combination with electrical apparatus and an inclosing'casingtherefor, of means for continuously supplying dehy drated fluid to thecasing to maintain an outward pressure slightly greater than that of theatmosphere.

"2. The combination with electric apparatus and an inclosing casingtherefor, of a relatively high-measure storage reservoir, a pump forsupplying dry air thereto, and means for supplying dry air from thestorage reservoir to the casing at a reduced pres-' sure.

3. The combination with an electric trans: former and an inclosingcasing therefor,- of a relatively high-pressure storage reservoir, achamber containing hygroscopic material, a reducing valve between theinclosing casilrg and the storage res rvoir, and means for forcing theair through the hygroscopic materlal into the storage reservoir fromwhich it is discharged at relatively lowl a pressure into the casin 4.The combination with an electric transhygroscopic material, and :1V pumpfor forc- 10 mg lnsulating fluld through the chamber "containing thehygroscopic material into ;the reservoir, dry air from the reservoirbeing continuously supplied to the casing.

In testimony whereof, I have hereunto subscribed my name this 21st, (laof July, 15

lVitnesses Hum-2N llux'rox,

B. 13. I'IINES.

